This invention relates generally to clothes dryers and, more specifically, to a variable speed blower for clothes dryers.
An appliance for drying articles such as a clothes dryer typically includes a cabinet including a rotating drum for tumbling clothes and laundry articles therein. One or more heating elements heat air prior to the air entering the drum. The warm air is circulated through the drum as the clothes and laundry items are tumbled to remove moisture from the articles in the drum. See, for example, U.S. Pat. No. 6,141,887.
At least one known clothes dryer utilizes an open loop control system to determine an appropriate amount of time for drying a load of clothes. The drying time is determined by an operator and entered using a manual control, such as a time selector switch. For the duration of the drying time, the heating elements are activated and deactivated to maintain warm air circulation inside the drum, and for more accurate control of the dryer heating elements, a temperature sensor is sometimes used in conjunction with the heating elements. The operator selects a drying time based on the desired dryness for the clothes and based on past experience with the particular machine. A longer drying time than is necessary to fully dry the clothes is commonly selected to ensure that the clothes are fully dried. Use of more time than is needed for effective drying, however, is wasteful.
While heating elements are often controlled to adjust air temperature, the blower on known residential dryers is driven at a constant speed for the total drying time. This constant speed may not facilitate lowering drying time, improving dryer efficiency, and reducing electrical energy consumption. Drying time is affected by the amount of heat that can be delivered to the clothes, which is influenced by airflow through the dryer. Airflow, in turn, is affected by many parameters, such as, ducting length and the number of bends, load size, lint filter condition, etc.
In one aspect, a dryer for tumble drying articles includes a drum including a cavity configured to hold articles to be dried, a first motor drivingly coupled to the drum to rotate the drum, a heat source in flow communication with the cavity, and a variable speed motor drivingly coupled to a blower positioned to deliver heated air from the heat source to the cavity.
In another aspect, a blower control system for a tumble type dryer having a variable speed blower motor driving the blower to supply heated air to the dryer cavity through a cavity inlet and exhaust air from the dryer cavity through a cavity outlet includes at least one temperature sensor positioned to sense a temperature associated with the dryer and generate a temperature signal representative of the sensed temperature, at least one pressure sensor positioned to sense a pressure associated with the dryer and generate a pressure signal representative of the sensed pressure, and a controller operatively coupled to the at least one temperature sensor and the at least one pressure sensor and configured to receive the temperature and pressure signals and control the operation of the variable speed blower motor based on at least one of the received signals.
In yet another aspect, a method for controlling a variable speed blower for a clothes dryer includes installing a controller on the dryer in communication with at least one temperature sensor and at least one pressure sensor, receiving a signal in the controller from the at least one temperature and pressure sensors, and controlling the blower motor based on at least one of the received temperature and pressure signals.